Department of Immunology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan.
J Immunol. 2010 Nov 1;185(9):5180-7. doi: 10.4049/jimmunol.1002026. Epub 2010 Sep 24.
The mitotic checkpoint is essential for maintaining genomic stability in differentiating B cells undergoing genetic alterations of the Ig gene. In this study, using real-time RT-PCR and in situ RNA hybridization, we demonstrated that MAD2 mRNA export is selectively regulated by Pcid2/Thp1. Pcid2 small interfering RNA induced a cell-cycle abnormality with increased apoptosis and polyploidy, as previously observed in MAD2-knockdown cells. Pcid2 small interfering RNA reduced MAD2 expression, but not the expression of other cell-cycle checkpoint proteins, such as MAD1 and BUBR1, or the cell-cycle-associated proteins, cyclin A, cyclin B1, and cyclin-dependent kinase 1. In mouse B lineage cells, Pcid2 transcripts appeared in a stage-dependent manner at high levels in bone marrow pre-B and immature B cells, and in spleen transitional 1 and follicular B cells, but at lower levels in pro-B, transitional 2, and marginal zone B cells, suggesting a stage-dependent requirement for MAD2 regulation. Cd19-cre-derived targeting of the Pcid2 gene induced a mature B cell deficiency in mice. These findings indicate that Pcid2 is essential for B cell survival through the regulation of MAD2 expression during B cell differentiation.
有丝分裂检查点对于维持 Ig 基因发生遗传改变的分化 B 细胞中的基因组稳定性至关重要。在这项研究中，我们使用实时 RT-PCR 和原位 RNA 杂交，证明 MAD2 mRNA 的输出受到 Pcid2/Thp1 的选择性调控。与以前在 MAD2 敲低细胞中观察到的情况一样，PCID2 小干扰 RNA 诱导细胞周期异常，增加细胞凋亡和多倍体。PCID2 小干扰 RNA 降低了 MAD2 的表达，但不降低其他细胞周期检查点蛋白（如 MAD1 和 BUBR1）或细胞周期相关蛋白（如细胞周期蛋白 A、细胞周期蛋白 B1 和细胞周期蛋白依赖性激酶 1）的表达。在小鼠 B 细胞谱系中，PCID2 转录本在骨髓前 B 和不成熟 B 细胞以及脾脏过渡 1 和滤泡 B 细胞中以高水平出现，具有阶段依赖性，而在 Pro-B、过渡 2 和边缘区 B 细胞中水平较低，表明 MAD2 调节具有阶段依赖性要求。由 Cd19-cre 介导的 Pcid2 基因靶向诱导小鼠成熟 B 细胞缺乏。这些发现表明，PCID2 通过在 B 细胞分化过程中调节 MAD2 的表达，对 B 细胞存活至关重要。
